To writer Bekah Brunstetter’s credit, her topical comedy-drama “The Cake” is substantially more than just another one of those cookie-cutter conversation pieces that seems to pride itself on simply being “ripped from the headlines.”

The origins of the play arose from the widely reported story about a Colorado baker who refused to make a wedding cake for a same-sex couple on the grounds that it conflicted with his religious beliefs. The subsequent legal battle, weighing matters of free speech against those of unlawful discrimination, went all the way to the U.S. Supreme Court.

“The Cake” wisely refrains from resorting to any lawsuits or courtroom theatrics, opting for a highly personal touch instead. Among Brunstetter’s new layers and textures are these elements: she relocates the story to the Bible belt (small-town Winston, North Carolina); she reassigns the gender of the baker and the gay couple from male to female; and she adds a racial element to the feminist mix by having one of the brides be black.

In director Lauren Morris’ warm and flavorful Horizon Theatre production, that character is played by the excellent Parris Sarter (“Angels in America” at Actor’s Express). “I’m a woman, who’s also black and agnostic and queer,” her character Macy complains at one point. “Nothing in this world ever fits for me.”

Almost as troubling to the baker, Della (Marcie Millard), is that Macy doesn’t eat sweets, either. A devout Southern Baptist and aspiring contestant for a TV show called “The Great American Baking Show,” Della is the longtime best friend to the late mother of Macy’s intended, Jen (an agreeable Rhyn McLemore Saver, from True Colors’ “Dot”), who unwittingly puts Della in a spiritually compromising position by asking her to make their wedding cake.

Many impassioned debates ensue among the three of them about sexual orientation and organized religion, about social bigotry and political intolerance, and about the skeletons in each of their family closets. Besides all that, Jen and Macy still have some emotional baggage to work through in their own relationship. And so do Della and her redneck-character husband, Tim (the fine Allan Edwards, of “The Pitmen Painters” at Theatrical Outfit).

Brunstetter (a writer and producer of the TV series “This Is Us”) occasionally spreads things on a little thickly with so many subplots, back stories and hot-button topics—or, as Della puts it in one of her plain and simple food analogies, “trying too hard to be original” by repurposing a generally light and fluffy recipe with ingredients that often feel heavy and overstuffed.

The irrefutably delicious icing on Horizon’s “Cake” is Millard’s richly measured performance as Della. She has long ranked among Atlanta’s best and most consistently enjoyable talents, primarily as a musical-comedy character actress: in Atlanta Lyric’s “Annie,” Aurora’s “Mamma Mia!,” City Springs’ “42nd Street,” and scores of other shows through the years.

On rare occasions, she has proven herself to be a powerful dramatic force to be reckoned with, as well; somewhat shamefully, if not inexcusably, her bravura turn as Maria Callas in Stage Door’s “Master Class” was nearly a decade ago.

Even so, fans may not be quite prepared for the marvelous level of Millard’s intricate work here, which has the simultaneous effect of both grounding and elevating the play, with a heartfelt humanity that’s genuinely amusing in scenes that could have been merely silly, and then unexpectedly poignant in others that might have seemed overwrought in lesser hands.

Call it a case of Millard having her cake and eating it, too—and savor every moment of it.

THEATER REVIEW

“The Cake”

Through June 23. 8 p.m. Wednesdays-Fridays; 3 and 8 p.m. Saturdays (no matinee on June 1); 5 p.m. Sundays; 11 a.m. Thursday (June 20 only). $27-$50. Horizon Theatre, 1083 Austin Ave. NE (in Little Five Points), Atlanta. 404-584-7450. www.horizontheatre.com.

Bottom line: A delicious showcase for the marvelous Marcie Millard.